1. Technical Field
This invention relates to improved sucker rod guides and paraffin scrapers useful in reciprocating oil wells.
2. Background Art
Normally, sucker rods in pumping oil wells are reciprocated therein during the pumping act. Well borings are sledom straight, hence rods without bushing or guides will frequently engage the tubing inner wall. Such engagement will weaken and wear both rod and tubing, causing ruptured tubing or broken and lost rod sting, resulting in expensive repairs and non-production, or frequent pulling of the rods for inspection and replacement. Also, many types of crude oil are paraffin based and often the temperature gradient, in the well bore, is such to cause paraffin build-up inside the tubing, that inhibts the flow of oil and eventually production is cut off.
A wide variety of rod guides and paraffin scrpaers have been developed in an effort to solve these problems. Of over 100 patents that have been issued, only a few have gained wide acceptance. A design, shown in V. C. Garrot's U.S. Pat. No. 1,696,543, issued in 1928, has two identical halves with central bores that fit over the outer diameter of the rod and slide together using a tongue and groove concept for fitting the halves and tightening to the rod. Another basic feature of Mr. Garrot's design was four ribs radially spaced 90 degrees apart and running lengthwise of the rod guide. This tool is easily installed or replaced in the oil field, and has become a standard design used by manufactures of today.
The features of these designs are good concepts, and have had considerable success, but the 90 degrees spacing of the four ribs does not allow a full circle or 360 degree guiding and scraping action. In other words, the tubing is not cleaned fully around the inner wall. To combat this problem, many users have added a rod string rotator, an expensive additional piece of equipment.
A similarly of Mr, Garrot's design was used in 1968 by U.S. Pat. No. 3,399,730 and again in 1982 by U.S. Pat. No. 4,343,518. The 1982 patent featured two designs: the standard design, mentioned above, used as a rod guide; and a unique design, featuring a wrap-over rib, illustrated in FIG. 7 of the specification, that follows the round contour of the tubing inner wall to scrape and direct paraffin. But the ribs have such a small amount of surface area, which will wear away much quicker than the thicker full length sides.
U.S. Pat. No. 4,088,185, issued in 1978, has four ribs and is also similar to Mr. Garrot's design; but it has been adapted to mold directly to the sucker rod. This mold-on design has the same problems, mentioned earlier, of not cleaning and guiding fully around the inner wall of the tubing.
My invention uniquely solves these problems by contacting fully around the inner wall of the tubing. The offset ribs fully cover the flow channels and allow a full circle of 360 degrees of cleaning, scraping and bushing action. It will be used as a rod guide or a paraffin scraper, and will be adapted to be manufactured as both a mold-on guide and scraper, or a field installed guide and scraper.